Concrete walls are made on site providing a gap between two formwork panels that are arranged such that they are facing one another. Said panels are secured to one another by means of transverse tie rods which have threaded ends and which project from the formwork panels to enable screwing in the corresponding nuts.
Once the panels are secured to one another, concrete is poured into the gap which is arranged sandwiched between the formwork panels. To prevent the concrete from adhering to the transverse bolts once it has set, these bolts are usually covered by or placed inside a tube beforehand. Once the concrete has set, the formwork panels and the transverse bolts are disassembled. Upon being disassembled, said bolts generate through holes on the concrete wall that must be closed and sealed to prevent leaks in the wall.
Extraction of the tube is optional and largely depends on the application of the wall. For example, in concrete walls intended for containing a fluid in which correct sealing of the wall is very important, such as, for example, water tanks, swimming pools, lubricant tanks, etc., it is suitable to extract said tube for assuring the leak-tightness of the wall.
In this sense, U.S. Pat. No. 5,813,185 discloses a cylindrical tube housing therein a transverse tie rod which is used for securing two formwork panels arranged parallel to one another. A conical end is removably coupled at each end of the tube.